冻结水泥改良粉质黏土的损伤力学特性研究

Study on damage mechanical properties offrozen cement-improved silty clay

为了探究滨海粉质黏土经水泥改良后的冻土力学特性,进行了不同冻结温度、含水率、水泥浆掺量及养护龄期条件下的单轴压缩试验,根据其应力-应变曲线特征,分析了水泥改良冻土的强度与各因素之间的内在联系。结果表明,水泥改良土的强度随冻结温度和含水率的降低而增加,且对冻结温度的敏感度较大。水泥浆掺量的增加会导致冻土的强度提高,但增长幅度随掺量的增加有所减缓。养护龄期对水泥改良土的强度影响显著,在养护28 d以后强度仍有缓慢增长。根据水泥改良冻土的应力-应变特征,结合损伤力学理论,以轴向应变表征微元强度,并假定服从Weibull分布,建立了水泥改良冻土的统计损伤本构模型,经试验验证,此模型能较好地描述土体的损伤演化规律。

In order to explore the mechanical properties of frozen soil of coastal silty clay improved by cement,uniaxial compression tests were carried out under different freezing temperatures,moisture contents,cement slurry contents and curing ages.On the basis of the stress strain curve characteristics,the internal relationship between the strength of cement-improved frozen soil and various factors was analyzed.The results show that the strength of cement-improved soil increases with the decrease of freezing temperature and moisture content,and the sensitivity to freezing temperature is greater.The increase of cement slurry content can lead to the increase of the strength of frozen soil,but the growth rate drops with the increase of slurry content.The curing age has a significant effect on the strength of cement-improved soil,and the strength still increases slowly after 28 days of curing.According to the stress strain characteristics,combined with the theory of damage mechanics,the statistical damage constitutive model of cement-improved frozen soil is established by using the axial strain to characterize the micro-element strength and assuming that it obeys Weibull distribution.The experimental results show that the model can describe the damage evolution law of soil well.